Add a property-test to exercise parsing logic

eventsource-client/Cargo.toml

@@ -27,6 +27,8 @@ maplit = "1.0.1"
 simplelog = "0.5.3"
 tokio = { version = "1.2.0", features = ["macros", "rt-multi-thread"] }
 test-case = "1.2.3"
+proptest = "1.0.0"
+
 
 [features]
 default = ["rustls"]

eventsource-client/src/event_parser.rs

@@ -289,6 +289,11 @@ impl EventParser {
 
         if let Some(incomplete_line) = self.incomplete_line.as_mut() {
             if let Some(line) = lines.next() {
+                assert!(
+                    !line.is_empty(),
+                    "split_inclusive should never yield an empty line"
+                );
+
                 trace!(
                     "extending line from previous chunk: {:?}+{:?}",
                     logify(incomplete_line),
@@ -370,6 +375,7 @@ impl EventParser {
 #[cfg(test)]
 mod tests {
     use super::{Error::*, *};
+    use proptest::proptest;
     use test_case::test_case;
 
     fn field<'a>(key: &'a str, value: &'a str) -> Result<Option<(&'a str, &'a str)>> {
@@ -666,4 +672,13 @@ mod tests {
         std::fs::read(format!("test-data/{}", name))
             .unwrap_or_else(|_| panic!("couldn't read {}", name))
     }
+
+    proptest! {
+        #[test]
+        fn test_decode_and_buffer_lines_does_not_crash(next in "(\r\n|\r|\n)*event: [^\n\r:]*(\r\n|\r|\n)", previous in "(\r\n|\r|\n)*event: [^\n\r:]*(\r\n|\r|\n)") {
+            let mut parser = EventParser::new();
+            parser.incomplete_line = Some(previous.as_bytes().to_vec());
+            parser.decode_and_buffer_lines(Bytes::from(next));
+        }
+    }
 }